It is well understood that “minimally invasive” as opposed to open surgical approaches often offer benefits in terms of decreased patient trauma, increased patient acceptance, improved recuperation time, and lower associated costs—both monetarily and in terms of other metrics. Accordingly, instances of minimally invasive procedures are increasingly common.
However, in any case where a medical practitioner advances a device to a remote operative site (e.g., open surgical procedure with a remote operative site, percutaneous access, and/or access via an open body conduit) alignment or orientation difficulties with the subject device may arise. For example, various parts of the anatomy may create a situation where the access path is offset from the treatment site. Such examples include the tortuosity of the vasculature, turns of the colon, regions of the stomach not in direct alignment with the path of the esophagus, and the branching of bronchi.
Tortuous anatomy may also create challenges when the particular treatment device requires mechanical actuation of the treatment portion. In particular, attempting to actuate a member may be difficult if the actuation force applied at the operator's hand-piece must translate to the distal end of the device.
In addition to basic considerations of navigation and site access, there exists the matter of device orientation at the treatment site. Many treatment devices make contact or are placed in close proximity to the target tissue. Yet, if the access path is misaligned from the treatment site, then difficulties may arise in attempting to and achieve uniform contact (or near contact) at the desired treatment site.
As one example, commonly assigned U.S. Pat. No. 6,411,852, incorporated by reference herein, describes a device having flexible electrode members that can be expanded to better fill a space (e.g., the lumen of an airway.) However, the tortuous nature of the airways may cause significant bending and/or flexure of the distal end of the device. The flexure may impose non-uniform forces on the flexible electrode as a result of the airway wall. These non-uniform forces may result in distortion of one or more of the flexible electrodes. Aside from the possibility of damaging the device, distortion of the device may impact the treatment.
For many treatment devices, the distortion of the energy transfer elements might cause variability in the treatment effect. For example, many RF devices heat tissue based on the tissue's resistive properties. Increasing or decreasing the surface contact between the electrode and tissue, often increases or decreases the amount of current flowing through the tissue at the point of contact. This directly affects the amount of heat in the tissue. Similar concerns may also arise with resistive heating elements, “cold” devices, or any energy transfer device. In any number of cases, variability of the energy transfer/tissue interface causes variability in treatment results. The consequential risks range from an ineffective treatment to the possibility of patient injury.
Furthermore, most medical practitioners recognize the importance of establishing acceptable contact between the transfer element and tissue. Therefore, distortion of the transfer element or elements increases the procedure time when the practitioner spends an inordinate amount of time adjusting a device to compensate for or avoid such distortion. Such action becomes increasingly problematic in those cases where proper patient management limits the time available for the procedure.
For example, if a patient requires an increasing amount of medication (e.g., sedatives or anesthesia) to remain under continued control for performance of the procedure, then a medical practitioner may limit the procedure time rather than risk overmedicating the patient. As a result, rather than treating the patient continuously to complete the procedure, the practitioner may plan to break the procedure in two or more sessions. Subsequently, increasing the number of sessions poses additional consequences on the part of the patient in cost, the residual effects of any medication, etc.